The weekly parashah or Torah reading has many perushim, commentaries, written about it. Did you ever wonder how are these two words related? Perush is the meaning of something. Rashi’s perush or elucidation on the Bible and Talmud is the most celebrated perush of all.
Both parashah and perush come from parash, meaning separate. This is clear from Rabbi Tzadok’s advice in Pirkei Avot (4:7), “Do not tifrosh from society” — do not separate yourself from your community. A parashah is a section, a distinct unit. A perush makes something distinct, clear.
For example, Numbers 15 describes a man gathering wood on the Sabbath. “He was placed in custody, for it had not been parash what should be done to him.” Moses awaited God’s perush or clear-cut direction.
Pesher, which has the same letters but with the r and the sh reversed, appears in Ecclesiastes and Daniel, meaning explanation or solution — almost the same as perush. King Solomon asks in Ecc 8.1: “Who is the wise one, and who knows the meaning (pesher) of these words?”
When two letters in a word switch places to form a new word, it is called metathesis. The Dead Sea Scrolls contain many pesher works, interpretations of the Bible from the Second Temple Period.